This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This proposal is focused on biomedical diagnostics for early detection of cancer. Specific detection of cancer biomarker proteins in serum is critical for early cancer detection, leading to improved patient prognoses, treatment success, and even cancer prevention. Our goal is to develop nanomaterial-based arrays for ultra-sensitive simultaneous detection of collection biomarker proteins for specific forms of cancer. Such devices feature vertical "forests" of single-walled carbon nanotubes (SWNT) with capture antibodies attached. The nanotube forests will be fabricated into immunosensor arrays featuring electrochemical detection of biomarker proteins via enzyme labels. SWNT forests provide high surface area for attachment of antibodies, leading to highly sensitive detection. There are a number of established protocols for assembling 20-100 nm vertically aligned SWNT arrays on surfaces in nm-scale acting as electrical conduits between transducers and active biomolecules. Recently, we used an amplified sandwich immunological assay with antibody-antigen captured on magnetic beads and LBL enzyme tracers loaded on SWNT, maximizing the number of enzyme tracers per binding event. Such assays allowed detection of DNA and proteins down to 80 copies and 2000 protein molecules, respectively. In our preliminary results we demonstrated prototype amplified immunosensor based on SWNT forest with excellent detection limits of 0.25 Fmol mL-1 for prostate specific cancer biomarker in serum using giant molecular tag, CNT-HRP-Ab2 conjugates with HRP/Ab2 ~ 300. The peroxidase-linked amperometric immunoassay used enzyme-catalyzed reduction of hydrogen peroxide to provide the signal. This prototype sensor is better than all competing immunoassays for PSA, and offer great promise for ultra-sensitive detection of disease biomarkers. Such a sensor protocol require tiny sample and is a rapid simple process amenable to immunoarray fabrication. To achieve highest sensitivity, we will further eliminate non-specific binding and optimize the signal amplification protocol. Finally, we will integrate optimized fabrication/detection approaches into multi-protein SWNT-antibody arrays for collections of cancer biomarkers.